U.S. Pat. No. 2,598,411 discloses the rearrangement of halogen atoms in perchlorofluoroalkanes by the shifting of like halogens to different carbon atoms using AlCl.sub.3, AlBr.sub.3, and their mixtures with antimony halides as catalysts. Carriers such as sintered aluminum fluoride or activated charcoal, on which the catalysts may be deposited, are disclosed.
GB 873,212 discloses a process for the manufacture of CF.sub.3 CHClBr by shifting a fluorine atom and the bromine atom of CF.sub.2 BrCFHCl using AlCl.sub.3. The patent teaches that if one attempts to isomerize chlorofluorohydrocarbons with AlCl.sub.3, HCl is lost and the corresponding ethylene derivative is obtained even under mild conditions.
U.S. Pat. No. 3,087,974 discloses a method of rearranging perfluorochloroethanes by contacting said perfluorochloroethanes at temperatures between 150.degree. and 600.degree. C. with a catalyst prepared by reacting activated alumina with a lower fluorocarbon having not more than one hydrogen atom. For example, the patent teaches that, when CH.sub.3 CF.sub.2 Cl is passed over activated alumina at about 300.degree. C., dehydrofluorination occurs and CH.sub.2 =CClF is produced.
JP 53-121710 discloses the isomerization of chlorofluorocarbons containing one or two hydrogen atoms by contacting them with catalysts represented by the formula AlCl.sub.x F.sub.y O.sub.z ; where x+y+z=3, 0&lt;x&lt;3, 0&lt;y&lt;3, and 0.ltoreq.z.ltoreq.3/2. In all cases only fluorine and chlorine atoms exchange positions. The isomerization is more effective, i.e., catalyst life is prolonged, in the presence of perchloro- or perchlorofluorocarbons cofeed. The highest temperature used is about 300.degree. C. since, above this temperature, starting materials are said to be decomposed.
U.S. Pat. No. 3,787,331 discloses catalysts made from AlF3 containing manganese, chromium and/or nickel which are used for the fluorination of perchlorofluorocarbon, CF.sub.2 ClCFCl.sub.2 to CF.sub.2 ClCF.sub.2 Cl with reduced isomerization of the starting material to CF.sub.3 CCl.sub.3. More isomerization is observed when using pure AlF.sub.3 as catalyst.
DT 2,245,372 discloses the preparation of di- and trifluoroethane compounds of general formula CF.sub.2 ZCZ.sub.3 or CF.sub.3 CZ.sub.3 in which Z=H, Cl, Br, or I, by isomerization of CFZ.sub.2 CFZ.sub.2 or CF.sub.2 ZCFZ.sub.2 using as catalyst a mixture of aluminum halides of the type AlXY.sub.2 and AlX.sub.2 Y in which X and Y are Cl, Br, or I. In one example Br and F atoms exchange places in CF.sub.2 BrCFHCl to yield CF.sub.3 CHBrCl.
Processes for the isomerization of hydrogen containing fluorohalocarbons as discussed above are known. However, the process of the instant invention provides the isomerization of fluorohydrocarbons, compounds containing only carbon, fluorine and hydrogen atoms, wherein fluorine and hydrogen atoms exchange places on the carbon skeleton.